MECHANISM OF INTERACTION OF THE COMPONENTS IN CATALYSTS FOR ELECTROREDUCTION OF HYDROGEN-PEROXIDE - MODIFYING NICKEL WITH PALLADIUM AND A PALLADIUM-CADMIUM COMPOSITION

The surfaces of nickel electrodes that were promoted by a contact depo sition of Pd or a Pd-Cd composition are examined using cyclic voltamme try. It is shown that the deposition of Pd leads to the formation of f inely divided deposits, providing a higher electrocatalytic activity o f such electrodes in reactions involving H2O2. The composition of the surface of the electrodes is investigated using X-ray photoelectron sp ectroscopy. Palladium microdeposits on nickel are found to possess an excess positive charge; after nickel oxidation, especially in contact with oxidized cadmium, these deposits possess an excess negative charg e. The modification by a Pd-Cd composition leads to changes in the che mical composition of the surface and to an intense metal-oxide interac tion within the Ni-Pd-Cd system, which ensures a high activity and sta bility of such electrocatalysts.